In the large urn are 1999 maize balls and 2000 blue balls (sorry about that, MSU fans). Next to the urn is the large pile of blue balls. The following process is performed repeatedly: Two balls are drawn from the urn; if both are blue, then one is put back and other thrown away; if both are maize, then they're both thrown away and a blue ball from the pile is put in the urn; and if they are of different colors, then the maize one is put back in the urn and the blue one is thrown away. Find out the color of the last ball in the urn (and must the time be reached at which the urn has just one ball left)? Obviously you need justification for your claims.